What I read was " the Saum is an amazing cartridge and throated has an advantage over the SS" and " you said " loaded with the same powders, pressure yada yada, they are similar and the 7 wsm is more!
I don't recall selling you one, but if I did, my apologies for your data!
Ok so we need facts do we?
I have no vested interest in this build however you do so lets get some facts on the table.
I have shot out over 10 7mm SAUM barrels and a WSM barrel and know one of your customers with a 7mm SSM.
As for barrel life a 30 or 40 degree shoulder makes almost no difference in performance or barrel life. We have built and shot exact rifles the only difference was the 6mm Dasher Vs 6mm BRX one has 40 and the other 30 degree shoulder same performance on both same barrel life.
Next neck length Rich you remember when SAUM brass was unobtanium and people were resizing WSM brass shooting it in F Class with a longer neck? Of course you do. Well i can tell you that there was no barrel life difference between either there is a lot more varience in barrel life by the way you shoot like shooting it hot and what powder you use. If say you used VV N165 its fairly cold and gives good veocities compared to say RE17 that torches throats at max pressure especially in string firing.
Your cartrige had a neich that is it works realy well when trying to fit say a 180gr VLD into a short mag and still fit it in a 2.820" loaded length.
When loaded long im sorry it has no advantage over the 7mm SAUM.
Now if comparing the SAUM and SS ballistics in a long throated barrel these will be almost identical with the same loads compare that to a 7mm WSM that is getting on the large size for a Short Mag the WSM will give higher velocities than the other 2 but will use more powder. If you load the WSM with a cooler burning powder and load to the slower SAUM / SSM velocity you will get better brass life and similar barrel life. There is a reason most using a 7mm on a WSM case use the 7mm 300WSM it is because the 7mm WSM has to much capacity for long strings of fire for the slight performance gain and the nodes that target shooters are using.
As stated also any short mag with a 35° or higher shoulder angle is a look so harder to get to feed reliably however longer mags and some work can help solve these issues. The WSSM and WSMs are notorious for this in true short action double stack mags.
So to answer the ops question
A 7mm WSM would give him 3000fps with 180s in his situation i would see how they feed from the magazine. If the WSM case is not feeding easily id go with the 7mm SAUM as its a factory cartrige he can throat the rifle to take advantage of the mag length and gain performance. This means cheeper dies and potential of factory ammo if he needed to use it.
Lets cover brass well now you can get all 3 from reputable manufacturers so there isnt an issue however SAUM is going to be available from more sources than the SSM or the 7mm WSM.
